150mm long with 80mm of travel from 1.4mm thick fins.  The housing is 177.5mm long x 30mm wide x 15mm tall.  Each fin has a flat edge and a precise pointed edge with a 90 degree cut out.  The locking mechanism is simple with a printed spring that presses against the fins before moving the locking lever down, preventing the spring from returning.  No screws or hardware is required, only a little glue on the contact points of the two halves of the housing.

The fins, spring and lock should be put in place before gluing the housing together.  Theoretically 107 fins are needed however depending on the smoothness of the top surface your printer is able to produce, you may need fewer fins.  The print profile for the fins fits 27 on a standard 256 x 256 bed, so this will need to be printed 4 times to give 108 fins.  You may also find that a longer or shorter lock is needed to create enough tension to hold the fins in place so I have included two different sizes.  
 

When assembling, you'll have to play with how many fins to use to get the right smoothness and play in the movement.  Id recommend printing in PLA, or whatever your printer is able to produce a clean top surface.  Ironing should help but will extend printing time.

(NOTE: when using the shorter lock, the spring will need to be in the compressed and locked position in order to fit the top housing to the bottom).